In recent years, systems that acquire data in an environment where unspecified and many users carry communication devices that sequentially transmit chronological data, such as sensor information, and each of the users moves around have been reviewed.
For example, a technology for an information acquisition apparatus that acquires information from many information sending-out devices is known (for example, see Japanese Laid-open Patent Publication No. 2006-340168 and Japanese Laid-open Patent Publication No. 2011-70596). In the technology, on receiving identifying information that is sent out from an information sending-out device, an information acquisition apparatus registers in advance the received identifying information as a subject from which information is acquired. The information acquisition apparatus sequentially transmits sent-out information transmission requests to information sending-out devices sequentially according to the sets of identifying information that are registered as subjects from which information is acquired and acquires sets of sent-out information that are transmitted from the information sending-out devices.
There is another disclosed technology for a distribution measuring apparatus that acquires data in a way that the distribution measuring apparatus transmits a detection condition by radio to multiple sensors and receives response signals by radio from sensors that meet the transmitted detection condition (see, for example, Japanese Laid-open Patent Publication No. 2003-60655).
There is however a problem in that, when there are unspecified and many communication devices, the information processing device is not able to acquire an excess of sets of data of communication devices over the maximum allowable number of sets of data to be received.
For example, the conventional information acquisition apparatus sequentially transmits requests to transmit sent-out information according to sets of identifying information that are registered in advance as subjects from which information is acquired and then acquires sets of sent-out information that are transmitted from information sending-out devices. When there are unspecified and many information sending-out devices whose identifying information is unknown, however, the information acquisition apparatus is not able to acquire sets of data of the information sending-out devices in the first place.
Furthermore, for example, the distribution measuring apparatus of the conventional technology acquires data by receiving response signals from the sensors that meet the detection condition. When there are an excess of sensors that meet the detection condition over the maximum allowable number of sets of data to be received by the distribution measuring device, however, the distribution measuring apparatus is not able to acquire the excess of sets of data over the allowable number.